A conventional method for mounting solder balls on an integrated circuit substrate contains: a first fixture including a plurality of grooves, and each groove has an upper opening and a lower opening smaller than the upper opening and is served to receive a solder ball. A through hole is defined below a respective one of the plurality of grooves, and a vacuuming device is fixed below the first fixture and includes a vacuuming device formed therein and having a plurality of connecting orifices for corresponding to a plurality of through holes of the first fixture, the vacuuming chamber also has an air pore defined on a central portion thereof so that when air is drawn out of the vacuum chamber via the air pore, a plurality of solder balls are attached, and when air is fed into the vacuum chamber from the air pore, the plurality of solder balls are released. A turning assembly is mounted on two side of the vacuuming device so as to rotate the first fixture 180 degrees. A guiding plate is disposed below the first fixture and includes a plurality of apertures for corresponding to the plurality of grooves of the first fixture, each aperture is provided to hold the solder ball. A second fixture is secured above the guiding plate and is applied to accommodate the plurality of solder balls. In operation, the guiding plate is descended to connect with the first fixture, and the turning device rotates the first fixture and the guiding plate so that the second fixture moves back and forth on the guiding plate, hence the plurality of solder balls are placed into the plurality of grooves of the first fixture via the plurality of apertures of the guiding plate, and then the vacuuming device draws air out of the vacuum chamber through the air pore so that the plurality of solder balls are attached. Thereafter, the guiding plate is lifted to move away from the first fixture on the first fixture, and the turning device downwardly rotate the first fixture 180 degrees so that the plurality of solder balls on the first fixture face downwardly. A substrate is lifted, and air is fed into the vacuum chamber from the air pore so that the plurality of solder balls are released from the first fixture and are mounted onto a flux of the substrate, and then the substrate is moved downwardly, thereby finishing a ball mounting process.
However, a gap between the second fixture and the guiding plate cannot be controlled exactly, so such a conventional method is only applicable for each solder ball with more than 0.25 mm of size, and the plurality of solder balls are scraped easily in a ball placing process.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.